New Strep Vaccine Passes Crucial 1st Test
Vaccine May Safely Protect Against Common Strep Infections
Aug. 10, 2004 -- A new strep vaccine may soon offer protection
against one of the most common and potentially most deadly sources of
infection, according to early tests of the vaccine.
Group A streptococcal bacteria are responsible for a variety of
illnesses, ranging from rheumatic fever and necrotizing fasciitis (flesh-eating
bacteria) to strep throat, and present a global health threat.
A vaccine to prevent these bacteria has been under
investigation for more than 70 years, but researchers say recent advances have
finally allowed them to overcome some of their previous obstacles.
For example, a major side effect of early vaccines was that
they contained proteins known as M proteins that help protect against infection
from streptococcus bacteria but also carry the risk of dangerous
cross-reactions in the heart and other tissues.
But the study, published in the Aug. 11 issue of The Journal
of the American Medical Association, provides the first evidence that a new
type of vaccine using a hybrid type of protein can provide protection against
streptococcus bacteria without triggering dangerous cross-reactions.
Strep Vaccine May Become Reality
The findings are based on the phase 1 clinical trial of the
vaccine, which was designed to evaluate the safety of the vaccine in
The study included 28 adult volunteers aged 18 to 50 who
received three injections of the vaccine in varying doses between October 1999
and February 2003.
After one year of follow-up, researchers found the vaccine was
well tolerated and did not cause any tissue cross-reactions or other
The vaccine also caused significant increases in the body's
immune system defenses (antibodies) against streptococcus infection.
Researchers say the results provide them with a dose (200 mg)
and a schedule that appear to be effective in providing protection against
strep infections without significant side effects.
In an editorial that accompanies the study, Michael E.
Pichichero, MD, of the University of Rochester Medical Center, says these
results are promising but many challenges remain before a strep vaccine like
this can be approved for widespread use.
"Most likely the proposed safety assessment will continue
in adults and eventually will progress in phase 2 studies in children,"
writes Pichichero. "There will be a need to conduct large ... trials
involving 10,000 to 60,000 participants to provide assurance that rare adverse
events are not associated with vaccination."